package com.flyu.myReflection;


import java.lang.annotation.*;
import java.lang.reflect.Field;

// 通过反射获取注解
public class TestReflect6 {
    public static void main(String[] args) throws NoSuchFieldException {
        // 获取反射
        Student2 student2 = new Student2();
        Class c1 = student2.getClass();
        // 通过反射获取注解
        Annotation[] annotations = c1.getAnnotations();
        for (Annotation annotation : annotations) {
            System.out.println(annotation);
        }
        // 获取注解的value
        Tablekuang tablekuang = (Tablekuang) c1.getAnnotation(Tablekuang.class);
        String value = tablekuang.value();
        System.out.println(value);

        // 获取类指定的注解
        Field f = c1.getDeclaredField("name");
        Fieldkuang annotation = f.getAnnotation(Fieldkuang.class);
        System.out.println(annotation.columnName());
        System.out.println(annotation.type());
        System.out.println(annotation.length());

    }
}

@Tablekuang(value = "db_student")
class Student2{
    @Fieldkuang(columnName = "db_id", type = "int", length = 10)
    private int id;
    @Fieldkuang(columnName = "db_name", type = "varchar", length = 3)
    private String name;
    @Fieldkuang(columnName = "db_age", type = "int", length = 10)
    private int age;

    public Student2(){
    }

    public Student2(int id, String name, int age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

// 类名的注解
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@interface Tablekuang{
    String value();
}

// 属性的注解
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@interface Fieldkuang{
    String columnName();
    String type();
    int length();

}